I lived in apartments for many years, but managed to stay on hf with 
whatever amount of wire I could get out a window to a tree.

Howard is correct about a counterpoise.

I had one for 40, 30, and 20 meters. You can connect them all to the ground 
terminal of your tuner. I found that I didn't need to remove any of them 
from the circuit at any time.

Just as with a dipole or 1/4 wave vertical, the 40 meter counterpoise will 
tune 15 meters reasonably, and the 30 meter wire will do the same for 10 
meters.

The length isn't too critical. I used cheap speaker wire from Wally World, 
which I pulled apart and cut into approximate 1/4 wave lengths for the 3 
bands.

The lengths were approximately 33, 23, and 16 feet.

My end fed wire was about 100 feet.

With these counterpoise wires connected, everything tuned much better, even 
80 meters. I never tried to wrap an 80 meter counterpoise around the 
apartment.

With the wire length I was using, I couldn't tune 30 meters at all without a 
counterpoise.

I also made one for 10 and 15 meters, but found I didn't really need them 
with the other 3 connected.

When I first started working with them, I would toss the 40 meter wire out 
the window late at night in order to have more of it stretched out. I got 
tired of having to reel the thing in and out every time I wanted to operate, 
and just ran it around the baseboard of my bedroom. I found that running it 
that way didn't make a significant difference in the way the antenna tuned 
vs tossing it out the window.

You do have to remember to not grab the wires while transmitting. Even at 5 
watts they will get your attention!

The counterpoise is a much more economical form of hocus pocus than the 
"artificial ground" boxes.

Mike Duke, K5XU
American Council of Blind Radio Amateurs